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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Carbohydrate Regulation Of Leaf Development: Investigating The Role Of Source Strength, Carbon Partitioning And Hexokinase Signaling In Regulating Leaf Senescence , Adam Christopher Miller Jan 2000

Carbohydrate Regulation Of Leaf Development: Investigating The Role Of Source Strength, Carbon Partitioning And Hexokinase Signaling In Regulating Leaf Senescence , Adam Christopher Miller

Retrospective Theses and Dissertations

For many plants, growth in elevated CO2 leads to reduced rates of photosynthesis. To examine the role leaf ontogeny plays in acclimation; we monitored photosynthesis and some related parameters throughout the development of tobacco leaves under ambient and high CO2 conditions. The pattern of photosynthetic rate over time was consistent with the expected pattern for a typical dicot leaf for both. However, the photosynthesis pattern in high-CO2-grown tobacco was shifted temporally to an earlier maximum and subsequent senescent decline. Rubisco activity appeared to be the main factor regulating photosynthetic rates in both treatments. Therefore, we propose a new model for ...


Mechanisms Of Negative Regulation Of Protein Prenylation: Investigation Of Murine Guanylate-Binding Protein 1 , John Thomas Stickney Jan 2000

Mechanisms Of Negative Regulation Of Protein Prenylation: Investigation Of Murine Guanylate-Binding Protein 1 , John Thomas Stickney

Retrospective Theses and Dissertations

Covalent attachment of isoprenoid lipids to proteins is a post-translational modification that occurs on approximately 2% of all cellular proteins. Proteins that contain a CaaX motif as their final four amino acids are presumed to be targets for the addition of C15 or C20 isoprenoids by farnesyl transferase (FTase) or geranylgeranyl transferase I (GGTase I) respectively. This modification is generally believed to occur stoichiometrically, and irreversibly, in vivo. Thus, if prenylation is to be regulated, this control must occur prior to lipid addition. At the moment, there is little evidence that the enzymatic activity of prenyl transferases can be modulated ...


Genetic Variation And Evolution Of Equine Infectious Anemia Virus Rev Quasispecies During Long Term Persistent Infection , Prasith Baccam Jan 2000

Genetic Variation And Evolution Of Equine Infectious Anemia Virus Rev Quasispecies During Long Term Persistent Infection , Prasith Baccam

Retrospective Theses and Dissertations

Genetic variation has been observed in many viruses. Viruses that carry their genetic information in the form of RNA exhibit high mutation rates because the viral polymerase lacks proof-reading mechanisms commonly found in DNA polymerase complexes. The combination of high mutation rates, small genome size, and high replication rates results in a population of closely related viral genotypes, which are commonly referred to as a quasispecies. A consequence of the genetic variation in viruses is possible variation in viral phenotype of the quasispecies population. Furthermore, changes in viral phenotype may be a biologically important factor in progression of disease. Here ...


Interactions And Electron-Transfer Reactions Between Metalloproteins , Milan Miroslav Crnogorac Jan 2000

Interactions And Electron-Transfer Reactions Between Metalloproteins , Milan Miroslav Crnogorac

Retrospective Theses and Dissertations

Electron-transfer reactions are essential for life. Because metalloproteins are involved in electron transport in the cell, it is important to understand the factors that affect recognition, interaction, and reactions of these electron carriers. Cytochrome c is well-characterized electron-carrier protein. The heme protein cytochrome c and the blue-copper protein plastocyanin are well suited for kinetic and mechanistic studies since their structures are known in detail;We investigated the effects of site-directed mutations and viscosity on rate-limiting rearrangement within the complex of cytochrome c and plastocyanin and identified the reactive configuration of the complex. In the reactive configuration of the complex cytochrome ...


Characterization Of [Alpha]-Adrenoceptor-Mediated Contractile Responses In The Isolated Bovine Tail Artery And Vein And An Investigation Of Nerve-Mediated Contraction In The Bovine Tail Artery In Response To Electrical Field Stimulation , Marina Val Ioudina Jan 2000

Characterization Of [Alpha]-Adrenoceptor-Mediated Contractile Responses In The Isolated Bovine Tail Artery And Vein And An Investigation Of Nerve-Mediated Contraction In The Bovine Tail Artery In Response To Electrical Field Stimulation , Marina Val Ioudina

Retrospective Theses and Dissertations

The purpose of this study was to identify alpha-adrenoreceptor types and subtypes mediating contractile responses to adrenergic agonists in the bovine tail artery and vein and to investigate nerve-mediated contraction in the bovine tail artery in response to electrical field stimulation. Isolated tissue bath methods were used to study isometric contractile responses in vessel rings. Electrical field stimulation, under constant current conditions, was used to study vessel contraction as a result of neurotransmitter(s) release from sympathetic nerve terminals;Evidence was obtained for the presence of functional alpha1A- and alpha1D-adrenoceptors in the tail artery. Whether functional alpha 1B-adrenoceptors are present ...


Tissue Specific Expression And Regulation Of The Mitogen Regulated Protein Genes , John Tollen Fassett Jan 2000

Tissue Specific Expression And Regulation Of The Mitogen Regulated Protein Genes , John Tollen Fassett

Retrospective Theses and Dissertations

Mitogen Regulated Protein (MRP; also called Proliferin; or MRP/PLF) is a member of the Prolactin/Growth Hormone gene family. There is evidence that MRP/PLF is a uterine growth factor and an angiogenesis factor. Between four and six highly homologous MRP/PLF genes (mrp/plf ) exist in the mouse, but the significance of multiple genes has not been determined. MRP/Plf is produced at high levels during mid-gestation by the placenta, where expression is restricted to the trophoblastic giant cells. To better understand the regulation of the mrp/ plf genes in vivo, we have developed an assay to analyze ...


Bacteriophage Therapy: A Novel Method Of Lytic Phage Delivery , Ratree Platt Jan 2000

Bacteriophage Therapy: A Novel Method Of Lytic Phage Delivery , Ratree Platt

Retrospective Theses and Dissertations

The widespread emergence of multi-antibiotic resistant bacteria has increased the need for alternatives to conventional antibiotic therapy. Accordingly, a significant amount of effort has been made to investigate the potential use of bacteriophages as prophylactic and therapeutic agents for bacterial infections. In this study, molecular biological techniques were applied to construct a lysogen of lytic bacteriophage lambda in an attempt to combat with multi-antibiotic resistant bacteria by a novel method of lytic phage delivery;To accomplish this goal, two plasmid-based site-specific recombination (SSR) systems for integration and recovery of DNA constructs from Escherichia coli and Salmonella typhimurium chromosomes were developed ...


Analytical Chemistry At The Interface Between Materials Science And Biology , Janese Christine O'Brien Jan 2000

Analytical Chemistry At The Interface Between Materials Science And Biology , Janese Christine O'Brien

Retrospective Theses and Dissertations

This work describes several research efforts that lie at the new interfaces between analytical chemistry and other disciplines, namely materials science and biology. In the materials science realm, the search for new materials that may have useful or unique chromatographic properties motivated the synthesis and characterization of electrically conductive sol-gels. In the biology realm, the search for new surface fabrication schemes that would permit or even improve the detection of specific biological reactions motivated the design of miniaturized biological arrays. Collectively, this work represents some of analytical chemistry's newest forays into these disciplines;This dissertation is divided into six ...


Biochemical And Molecular Genetic Studies Of The Metabolic Role Of Methylcrotonyl-Coa Carboxylase , Ping Che Jan 2000

Biochemical And Molecular Genetic Studies Of The Metabolic Role Of Methylcrotonyl-Coa Carboxylase , Ping Che

Retrospective Theses and Dissertations

The physiological metabolic roles of methylcrotonyl-CoA carboxylase (MCCase) have been investigated. Radiotracer metabolic studies using extracts from isolated mitochondria and incubated with [U-14C]leucine and NaH14CO3, demonstrate that plant mitochondria can catabolize leucine via the following scheme: leucine ⇒ alpha-ketoisocaproate ⇒ isovaleryl-CoA ⇒ 3-methylcrotonyl-CoA ⇒ 3-methylglutaconyl-CoA ⇒ 3-hydroxy-3-methylglutaryl-CoA ⇒ acetoacetate + acetyl-CoA. These findings demonstrate for the first time that the enzymes responsible for leucine catabolism are present in plant mitochondria. We conclude that one of the primary metabolic roles of MCCase in plants is the catabolism of leucine;A single-copy gene encoding the Arabidopsis MCC-A subunit was isolated and characterized. It contains 15 exons separated by ...


Structure And Function Of A Novel Cap-Independent Translation Element In The 3' Untranslated Region Of A Viral Rna , Liang Guo Jan 2000

Structure And Function Of A Novel Cap-Independent Translation Element In The 3' Untranslated Region Of A Viral Rna , Liang Guo

Retrospective Theses and Dissertations

This research focuses on a cap-independent translation element (TE) we identified in the RNA of barley yellow dwarf virus (BYDV). Assisted by the TE, all messenger RNAs of BYDV, which include BYDV genomic RNA and subgenomic RNAs, are translated cap-independently. This allows uncapped, nonpolyadenylated BYDV RNAs to compete with capped and polyadenylated host mRNAs for the translation machinery. The core of the TE is a 105 nt sequence (TE105) located in the 3' UTR of BYDV genomic RNA. Due to its 3' position, at least two functions are necessary for TE105: 3 '--5' communication, and recruitment of translation machinery. TE105 ...


Characterization Of Intracellular Survival Of Mycobacterium Avium Subspecies Paratuberculosis In J774 Murine Macrophages , Jesse Michael Hostetter Jan 2000

Characterization Of Intracellular Survival Of Mycobacterium Avium Subspecies Paratuberculosis In J774 Murine Macrophages , Jesse Michael Hostetter

Retrospective Theses and Dissertations

Mycobacterium avium subspecies paratuberculosis (M. a. ptb) is the causative agent of Johne's disease, a progressive diarrheal disease of wild and domestic ruminants. Like other pathogenic species of mycobacteria, M. a. ptb is an intracellular pathogen of monocytes and monocyte-derived macrophages. In this dissertation we tested the hypothesis that M. a. ptb survives within macrophages by inhibition of acidification and maturation of the phagosomal compartment in which it resides;Chapter 1 consists of a general introduction and a literature review of recent reports concerning normal phagosomal maturation and maturation of the mycobacterial phagosome. Chapter 2 characterizes acidification of the ...


Expression Of Bovine Mammary Gland Ca2+Atpases , Siriwan Prapong Jan 2000

Expression Of Bovine Mammary Gland Ca2+Atpases , Siriwan Prapong

Retrospective Theses and Dissertations

Control of transcellular Ca2+ fluxes associated with lactation are critical to mammary function and Ca2+ homeostasis. Mammary Ca2+ transport and storage may contribute to the pathological hypocalcemia seen in dairy cows at parturition. RT-PCR and Western Blotting were used to identify which Ca2+ ATPases are present in the bovine mammary gland and in milk fat globule membranes (MFGM). PMCA1, PMCA2 and PMCA4 are plasma membrane Ca2+ ATPases expressed in the bovine mammary gland. A putative Golgi Ca2+ ATPase (bSPCA) is also found in significant amounts in the mammary gland. The expression of Ca2+ ATPases in the bovine mammary gland is ...


Characterization Of Skeletor: A Novel Nuclear Protein Implicated In Mitotic Spindle Assembly , Diana Lee Walker Jan 2000

Characterization Of Skeletor: A Novel Nuclear Protein Implicated In Mitotic Spindle Assembly , Diana Lee Walker

Retrospective Theses and Dissertations

The mAb 2A labels Drosophila embryos in a novel, dynamic staining pattern that identifies a nuclear meshwork during interphase, which is remodeled to form a spindle structure at metaphase. This intriguing pattern made the antigens recognized by mAb 2A interesting targets for cloning and analysis, Skeletor was found to be encoded by a complex locus. Two alternatively spliced transcripts from the Skeletor locus were identified, Orf1b/Orf2 and Orf1a. Orf1b/Orf2 has an unusual structure, containing two overlapping open reading frames with coding potentials of 87 kD and 81 kD respectively. Analysis of Orf2 amino acid content reveals overall high ...


A Role For Glutathione In Reactions Between Oxidants And Proteins , Robert Joseph Mallis Jan 2000

A Role For Glutathione In Reactions Between Oxidants And Proteins , Robert Joseph Mallis

Retrospective Theses and Dissertations

This dissertation examines the role of reduced glutathione (GSH) in the oxidation of proteins. Carbonic anhydrase III is a cytosolic protein which is S-glutathiolated in cells under oxidative stress. The pure protein was found here to be S-glutathiolated by two oxidants, 2,2'-Azobis(2-amidinopropane)dihydrochloride (AAPH) and hydrogen peroxide (H2O2). At physiologically relevant molar ratios of GSH to protein, GSH was found to mediate protection of carbonic anhydrase III from irreversible oxidation via S-glutathiolation. Both oxidants were found to react directly with the protein. S-glutathiolation. appears to result from the formation of an activated protein thiol that reacts with ...


Two Dimensional Models Of Tumor Angiogenesis , Serdal Pamuk Jan 2000

Two Dimensional Models Of Tumor Angiogenesis , Serdal Pamuk

Retrospective Theses and Dissertations

Angiogenesis, the formation of new capillaries from pre-existing vessels, is essential for tumor progression. It is critical for the growth of primary cancers. In this thesis we present a new approach to angiogenesis, based on the theory of reinforced random walks, coupled with a Michaelis-Menten type mechanism. This views the endothelial cell receptors as the catalyst for transforming angiogenic factor into proteolytic enzyme in order to model the first stage. In our model we use a curvature-induced proliferation term for the endothelial cell equation. Our numerical results indicate that the proliferation of endothelial cells is high at the tip. Also ...


Trna-Dependent Amino Acid Discrimination By Escherichia Coli Valyl-Trna Synthetase , Keith David Tardif Jan 2000

Trna-Dependent Amino Acid Discrimination By Escherichia Coli Valyl-Trna Synthetase , Keith David Tardif

Retrospective Theses and Dissertations

Valyl-tRNA synthetase (ValRS) has difficulty discriminating between its cognate amino acid, valine, and structurally similar amino acids, particularly threonine. To minimize translational errors, the enzyme catalyzes a tRNA-dependent editing reaction that prevents accumulation of misacylated tRNA Val. Replacing the universally conserved 3' terminal A of tRNAVal, particularly with pyrimidines (C or U), permits stable misacylation with threonine, alanine, serine, and cysteine. We also observe low levels of aminoacylation of wild type and 3'-end mutants of tRNAVal with isoleucine. ValRS is unable to hydrolytically deacylate misacylated tRNAVal terminating in 3' pyrimidines, but can deacylate tRNAVal terminating in purines (G or ...


Escherichia Coli Adenlyosuccinate Synthetase: Studies On Substrate Specificity , Andrea Gorrell Jan 2000

Escherichia Coli Adenlyosuccinate Synthetase: Studies On Substrate Specificity , Andrea Gorrell

Retrospective Theses and Dissertations

Enzymes are catalysts of biological reactions, and are characterized by their substrate specificity, specificity of reaction and ability to be regulated. Aspects of enzymes studied are the catalytic mechanisms, association states, origins of substrate specificity, and enzymatic regulation of the enzyme. One enzyme studied as a model system is adenylosuccinate synthetase (E.C. 6.3.4.4, L-aspartate:IMP ligase, GDP forming; AMPSase). Interactions which appear to be important for enzyme association and substrate binding were studied by producing site-directed mutants of AMPSase as guided by the unligated and ligated crystal structures. The wild-type and mutant enzymes were compared by ...


The Contributions Of The Hras C-Terminus And Its Lipid Modifications To Hras Signal Transduction Events And Membrane Binding , Michelle Ann Booden Jan 2000

The Contributions Of The Hras C-Terminus And Its Lipid Modifications To Hras Signal Transduction Events And Membrane Binding , Michelle Ann Booden

Retrospective Theses and Dissertations

In the GTP bound state, Ras proteins activate multiple downstream effector proteins, the combination of which regulate cell growth, differentiation, and changes in cell shape. However, Ras proteins must undergo C-terminal lipidation before they can support biological activity. Specifically, the C-terminus of the HRas protein must be modified by a farnesyl at Cys186 and two palmitates at Cys181 and Cys184. The current paradigm suggests that palmitate is not attached without prior farnesyl addition and that these post-translational lipid modifications are only necessary for membrane association. However, emerging evidence suggests that the C-terminus and its lipid modifications may also be responsible ...


Phylloquinone Biosynthetic Pathway , Thomas Wade Johnson Jan 2000

Phylloquinone Biosynthetic Pathway , Thomas Wade Johnson

Retrospective Theses and Dissertations

Photosynthesis converts solar energy into chemical energy to drive the biological processes of life on our planet. Photosystem I (PSI) is one of the two reaction centers of oxygenic photosynthesis in cyanobacteria and higher plants. PSI is a multisubunit membrane bound protein complex that catalyzes the photooxidation of plastocyanin in the thylakoid lumen and the photoreduction of ferredoxin in the cytoplasm. The PsaA/PsaB subunits form the heterodimeric core that harbors the primary electron donor P700 and acceptors A0, A1, and FX. Two electron acceptors, F A and FB, occupy PsaC one of three peripheral proteins bound to PSI. The ...


Molecular Interactions Of The Intermediate Filament Protein Synemin , Robert Milton Bellin Jan 2000

Molecular Interactions Of The Intermediate Filament Protein Synemin , Robert Milton Bellin

Retrospective Theses and Dissertations

Synemin is a large (∼182 kDa by sequence, ∼230 kDa by SDS-PAGE) cytoskeletal protein that was originally identified based upon its co-localization and co-purification with the intermediate filament (IF) proteins desmin and vimentin in muscle tissue. Studies in this dissertation have focused on understanding the molecular properties and role of synemin. Cloning and sequencing studies revealed that synemin itself is a large member of the IF protein superfamily because it contains the domain structure typical of IF proteins, i.e., an ∼310 amino acid, coiled-coil rod domain flanked by an N-terminal head domain, and a C-terminal tail domain that is ...